## How are drives used for Erasure Code?

MinIO divides the drives you provide into erasure-coding sets of *2 to 16* drives.  Therefore, the number of drives you present must be a multiple of one of these numbers.  Each object is written to a single erasure-coding set.

        assertEquals(0x0010, response.getAttributes());
        // getLastWriteTime returns lastWriteTime (from readUTime) + serverTimeZoneOffset
        // readUTime multiplies the seconds value by 1000, and writeUTime divides milliseconds by 1000
        // So the round-trip should preserve the milliseconds value
        assertEquals(sampleTimeMillis + serverTimeZoneOffset, response.getLastWriteTime());
        assertEquals(1024, response.getSize());

    int bytesToCopy = bufferSize - buffer.position();
    for (int i = 0; i < bytesToCopy; i++) {
      buffer.put(readBuffer.get());
    }
    munch(); // buffer becomes empty here, since chunkSize divides bufferSize

    // Now process directly from the rest of the input buffer
    while (readBuffer.remaining() >= chunkSize) {
      process(readBuffer);
    }

- **MinIO creates erasure-coding sets of _2_ to _16_ drives per set.  The number of drives you provide in total must be a multiple of one of those numbers.**
- **MinIO chooses the largest EC set size which divides into the total number of drives or total number of nodes given - making sure to keep the uniform distribution i.e each node participates equal number of drives per set**.